Optically active prostaglandin F.sub.2.alpha. has been isolated from natural sources. These compounds as well as the 15-epi-prostaglandin F.sub.2.alpha. compounds are known agents for inducing labor in pregnant women and for the therapeutic termination of pregnancy.
In the past, racemic prostaglandin F.sub.2.alpha. has been synthesized by Fried in the Journal of American Chemical Society, 94, 4342, 4343 (1972) and Corey, Tetrahedron Letters, 307, 311 (1970). While racemic prostaglandin is also active in inducing labor in pregnant women and terminating pregnancy, the racemic form of this compound is not as active as its optically active forms. Various procedures have been proposed for synthesizing the optically active forms of prostaglandin F.sub.2.alpha. utilizing resolving techniques. However, these procedures have been uneconomical and cumbersome. Therefore, it has been desired to provide a direct asymmetric synthesis of optically active prostaglandin F.sub.2.alpha. which avoids cumbersome resolution procedures.